
Phineas Flynn and his stepbrother, Ferb Fletcher, are determined to make every day of their summer vacation fun. They try building a full-scale roller coaster, becoming musicians, building a backyard beach, and traveling back in time to meet dinosaurs. Their family pet, Perry the Platypus, doubles as a secret agent and battles evil. Meanwhile, older sister Candace is tattling on them to Mom and Dad, though she can never seem to catch them in the act.

Meap enlists Candace and the kids to help bust his nemesis, Mitch, before he can steal a long-lost treasure hidden somewhere on Earth.

The boys bring Perry to the vet for a checkup and build a pet wash while they wait; Carl tries to help Perry stop Doof while working three other part-time jobs.

The Flynn-Fletchers take a cruise; Doof steals shrunken goods; Isabella struggles to lead the Fireside Girls on her own, while Doof renews his evil business license.

Buford's Candace suit comes to life and tries to take over the real Candace's life; Candace ignores her brothers for a day in order to help her Mom with a bust of her own.